The present invention relates to a ballistic protective textile structure and a method for making it.
More specifically, the present invention relates to a personal ballistic protective textile structure which is usually called “soft armor”.
As is known, the capability of a fabric material to reject a bullet or a penetration of a knife or pointed implement, essentially depends on the nature of the textile fibers used, the fabric material weave and the fabric material weight per surface unit, or fabric areal density.
A demand of improved small weight and comfortable fabric materials for the above applications is a main market requirement in several fields of ballistic protective garments.
At present, the main reinforcement fibers forming the ballistic protective fabrics substantially comprise para-aramid and ultra-high-molecular-weight polyethylene (UHMWPE) fibers, which, owing to their peculiar mechanical characteristics, are adapted to efficiently adsorb forces applied thereon.
In the so-called “UD” or unidirectional products, the reinforcement fibers, which are arranged with a parallel arrangement, are coupled to a suitable film or resin material, substantially operating as a glue for said fibers, to allow the fiber layer to be handled in making the protective device or garment, without causing the parallel arrangement of the fibers to be changed.
In this connection, it should be pointed out that the fiber weight/matrix ratio, jointly to the yarn and support material features, control the ballistic performance of the product.
The UD ballistic protective garments usually have a flexibility and draping capability less than that of textile approaches, thereby the garment comfort conditions are very poor.
In fact, the UD article parallel fiber arrangement and, mainly, the take-up of the weave, that is a straddling of the warp and weft yarns, are design parameters providing the textile material with a maximum resistance against bullets, fragments, knives, pointed implements and so on, since said fibers are all arranged with a parallel arrangement and aligned in a single axial direction.
Because of the above mentioned taking-up of the warp and weft yarns, and consequently because of an offset of the fibers away from their axis at warp and weft yarn overlapping points, the article mechanical strength values are usually less than those of the same fibers in an UD construction.
Using high toughness fibers, such as para-aramid and UHMWPE fibers, to provide overlapped unidirectional products is already known for applications in textile structures, both flexible and stiff.
The above structures can be further subjected to impregnating processes, to improve their impact resistance, while partially modifying their bending characteristics.
Conventional methods for making the above textile articles comprise an opening step of mechanically opening the fibers and a stabilizing step, by different thermoplastic matrix arrangements.
The above process, while allowing to properly exploit the yarns and reduce the finished product weight, on the other hand greatly reduces the mechanical characteristics of the yarns.
In this connection, it should be pointed out that different commercial approaches are at present available, of a non-monolithic nature, that is different from homogeneous fabrics, to meet different related standards, and providing articles resisting against conventional bullets, but not against those of military guns, in which case an improved protective capability is required, usually achieved by additional reinforcement plates (for example of ceramics and UHMWPE materials).